Sadly...not often enough. lol. The frequency of TC +3, depends on the game....mostly number of decks and penetration. TC+3 will occur more in double games than 6 deck games and will occur more often with deeper penetration. But for a very average 6 deck game, with 1.5 decks cut off (75% pen), about 9% of the time. For comparison, the same game with deeper penetration of 1 deck cut off will be roughly 11%. and a double deck game of average penetration could be as high as 13-14%.
But let's stick to the very common, very average 6 deck game at 75% pen. IF you play through every hand, whether the count goes negative, positive or neutral, you will see 9% at +3 or more. So for each 100 hands played, you will see TC +3, 9 times. But what if each time the count went negative, you jumped to another game, whether a game with a count already positive, as I try to do, or even just a new game starting at zero? Now for every 100 hands played you will see (and play) more TC+3's. You are basically increasing the number of max bet opportunities per 100 rounds played.
If the pit (or surveillance) is sitting there watching you and every round, sure they should notice this. But that is rarely the case. Pit personnel are actually spread pretty thin these days. One of the cost cutting things that the accounting corporate types implemented in recent years has been less pit personnel and more tables per pit person. Same with surveillance. Unless it is a particularly slow time, these guys and gals are usually fairly busy with chip fills, opening and closing tables, changing cards, and players from multiple tables buying in and cashing out. It is rare that a pit person is standing there watching me and my game and if they are, it is probably time to move on.
A sudden jump in bet isn't the problem. That occurs all the time, with system players, players parlaying wins and chasing losses. The problem is retreating back to that small, minimum wager at the shuffle after betting bigger the previous shoe. THAT is the big tell. You can avoid that by just moving on after you have shown your spread, rather than retreating back to the small wager. THIS is one of the advantages of Vegas. Just move on to the next game and/or casino.
And with that....I am off to the next casino. I already spent about an hour longer than intended to here this morning. lol